Inkjet printing has become a pervasive printing technology. Inkjet printing systems include one or more arrays of drop ejectors provided on an inkjet printing device, in which each drop ejector is actuated at times and locations where it is required to deposit a dot of ink on the recording medium to print the image. A drop ejector includes a pressurization chamber, a drop forming mechanism (e.g. a heater or a piezoelectric structure) and a nozzle. An inkjet printing device is an example of a fluid ejection device. Typically, inkjet printing devices or fluid ejection devices are fabricated as a plurality of die on a wafer. One or more die are then fluidically connected to a mounting substrate as part of the fluid ejection assembly, such as an inkjet printhead.
One way to reduce the cost of an inkjet printhead is to reduce the size of the fluid ejection device, i.e. the printhead die, which typically includes not only the fluid inlets and the arrays of drop ejectors, but also includes logic and switching electronics, as well as electrical interconnections. Due to advances in microelectronic fabrication processes, making the electronics on the die fit within a smaller space is now possible, so that the fluid inlets on the printhead die can be spaced as close together as 0.8 mm center-to-center or closer. The problem that remains is providing a mounting substrate having a die-attach portion with multiple fluid feed slots at the same spacing as the fluid inlet spacing on the printhead die.
Commonly assigned US Published Application No. 2008/0149024 (incorporated herein by reference) discloses a printhead substrate arrangement in which the portion of the substrate that includes the fluid feed slots or channels is made from a ceramic material, while the remaining portion of the substrate arrangement is made by insert molding, i.e. by molding plastic material around the ceramic portion. This arrangement provides for a ceramic mounting surface that is flat and stable and that has a coefficient of thermal expansion that is similar to that of the printhead die in order to facilitate low stress in the printhead die in the assembled printhead. However, the minimum slot to slot pitches typically achieved in a ceramic part made by a low cost powder compaction or dry press process, as might typically have been used to form the ceramic portion of the substrate in US Published Application No. 2008/0149024, are about 1.5 mm (0.7 mm wide slots with 0.8 mm thick walls).
What is needed is a mounting substrate where the widths of the fluid feed slots and the lands between the fluid feed slots are reduced to enable the overall reduction in the size of the corresponding printhead die to be attached. It is further desirable to have a mounting substrate that is low cost.